Sound film



Nov. zs,.1:=r.s. w WCHAE'US 2,136,143

SOUND- FILM Filed April 2, 1936 Yawn' Figil COMPOSITE COMPOSITE projection.

Patented Nov. 8, 1938 SOUND Walter Michaelis, Brussels, Belgium,

Bela Gaspar, Brussels, Belgium Application April 2, 1936,' Serial No. 72,395

Germany April 2, 1935 6 Claims.

This invention has for its chief object to provide a sound iilm having thereon several mutually independent sound records so arranged that during the showing of the film one or other of the sound records may be selectively and independently reproduced as desired. The chief advantage lies in the fact that it will enable the sound lm to be reproduced with the sound or speech in the original form lor in another language. From the following description of the present invention it will be seen that this choice between the different forms of sound reproduction is extremely simple and that by a single operation it is possible to change over from one sound record to the other. The sound recording is carried out in the usual manner and the reproducing apparatus in the cinematographic theatre remains substantially the same. In the simplest form of this invention a lter disc is merely placed in front of the sound tracks in order to effect the change from the one language to the other.

The principle which forms the basis of the present invention can be explained, in a simple manner, as follows:-When a sound film, such as is already used in coloured lms, contains a coloured sound track, recorded either by the variable width or the variable density method, a sound reproduction only occurs when the source of light employed for the reproduction contains or consists of rays which are absorbed by the coloured portions of the sound record. If a sound strip, which contains for example a red sound record, on a colourless ground is projected with red light, the light will pass through the coloured sound portions as much as through the non-coloured layer and consequently a control of the illumination by the sound track and a corresponding reaction of the light-sensitive cell will not take place. The cell will likewise not react when a blue sound record is projected .by blue light which it allows to pass through unweakened; when a yellow coloured sound record is projected by yellow light; or generally when a light which is not absorbed by the pigments or dyestuis forming the sound record is used for records, each of which is diierently coloured, are arranged side by side and illuminated with a light which is absorbed only by one of the differently coloured sound records, the sound reproduction corresponding to this one record alone takes place. If the light rays impinging on the sound records are changedwhich can be eifected in most simple manner by changing a colour Therefore, if two or more soundy filterso that the light now is absorbed only by one of the other coloured sound records, the sound reproduction corresponding to this second sound record alone will take place.

It is obviously not necessary for the differently coloured sound records to be arranged side by side. Ihey may, if desired, be arranged in such a manner that they partly overlap. It is only necessary for each of the different sound records to be coloured in such a manner that a portion 10 of the spectrum is absorbed, whilst those rays which are absorbed by the differently coloured sound records, i. e., those rays which are necessary for the reproduction of the other sound records are transmitted. It is obviously also possible to use for one of the sound records a colour absorbing invisible rays, e. g., infra-red or ultraviolet rays. In this case, however. the other records must allow the passage of the invisible rays employed for the reproduction of this iirst-mentioned sound record.

All methods of production which lead to coloured iilms are more or less suitable and, in most instances, it is advantageous to treat the image and the sound track by the same process, if possible, also in the same operation. Preferably there are employed printing or colouring processes, and particularly those processes in which metal deposit images are produced in several superposed light-senstive layers arranged on one side of the iilm, or on both sides, and dyestuii images corresponding to the metal deposits are produced by selective formation or destruction of the dyestufts at the image or non-image portions of the film. Several of these processes can also be employed at the same time. In sound films, the picture portion of which is coloured, the colouring of the sound records is preferably carried out with the aid of the same dyestuils which are employed for thezproduction of the picture portion of the multi-coloured picture. If the multi-coloured picture is in a single-layer, the independent sound records also lie in this layer. If for the picture portion a colour component picture is present in each of several 45 diierently coloured layers, the individual coloured and mutually different sound records are preferably also arranged in the different layers, the particular layers used being those coloured with the colour of the desired sound record. It will be seen that it is, therefore, possible without any diculty, to accommodate just as many sound records on one and the same coloured lm as there are colours employed to produce the picture; in two-coloured lms, two; in threecoloured films, three; and other films so on. It is also possible to'employ, in addition,v further I differently coloured sound records.

In order that this invention may be the more clearly understood, certain illustrative examples will now be described with reference to the accompanying drawing, in which Figure 1 illustrates the disposition of the colcured layers on the support, and

Figures 2, 3, 4 and 5 are diagrammatic views illustrating the disposition of the composite picture and sound images in the complete lm:

Figures 2, 3, 4a and 5' are exploded vieWS representing the individual layers of Figs. 2, 3, 4 and 5 respectively, and illustrate the manner in which the differently coloured images may be disposed in these layers.

Example 1.-The positive lm consists of a layer support a on which three coloured, difierently sensitized layers are arranged. On one side of the support a there is arranged a layer b coloured yellow with Chrysopheninel G (304) and sensitized for green light with erythrosine, this layer being poured or disposed over a purple-red layer c sensitized for red light coloured with Azofuchsine (146). On the other side of the support a,- there is a layer d rendered sensitive to` green light, for example, with erythrosine. (The numbers given after the dyestufs are the numbers under which these dyestuifs may be found in the Schulz Farbstofftabellen, 5th edition 1920). A colour separation picture is copied into each of the layers b, c and d of the positive iilm from positive copies of the original individual colour separation images. The blue selection copy is copied with green light and the green selection copy is copied with red light both from the double layered side of the film and the red selection copy is copied with green light from the single layered side of the iilm. In addition to these colour component pictures of the scene of the play, positive originals of the two sound records are copied in the two outer layers, viz., b and d, e. g., the soundoriginal corresponding to the English version of the sound is copied with green light from one side of the film and the sound original corresponding to a French version of the sound is copied on the other side likewise with green light. The purple colouring of the middle layer acts as a barrier and absorbs the light during both printing operations and so restricts the two sound copies to the two outer layers of the material. In the sound track portion of the purple coloured layer c a diffuse exposure is effected over the entire width of the sound track with the aid of red light so that a uniform silver deposit is produced in this layer. The iilm is then developed and xed and is treated with a dye-destroying reagent which destroys the dyestuffs at the points of the silver deposit. A suitable solution for effecting this local destruction of the dyestuis comprises a 5% solution of thiocarbamide with 2% citric acid. After the remaining silver has been removed by bleaching and fixing, a lm is obtained having in its picture portions the individual different colour separation pictures which supplement each other to form a bright three coloured picture. Mutually independent sound records, e

and f, one in a blue-green colour, the other in a' .range.

vdiilerent areas can overlap. At such ppints the sound track appears green in the arrangement chosen as shown in Figure 2 of the accompanying drawing. The two different yellow and bluegreen .coloured sound records are reproduced separately the one from the other.

For example, in the above mentioned arrangement, 'the sound track is illuminated with blue light in order to reproduce the yellow coloured sound track. The yellow coloured sound track then absorbs the blue light whilst the blue-green coloured sound track allows the same to pass freely. The light sensitive cell used must, in this case, be sensitive to blue light and a known type of cell consisting of a silver-silver oxide layer sensitized with caesium may be employed. Another cell may consist of a platinum surface on which is precipitated a layer of potassium of a thickness vgreater than one potassium atom. The maximum sensitivity of such a cell is situated at 360mg and consequently a short wave blue light is preferably used for illuminating the sound track. In order to reproduce the bluegreen coloured sound record the sound track is illuminated with red light. The cell must in this case be sensitive to red light. It is possible to use for this purpose the above-mentioned silver-silver oxide layer sensitized with caesium. The sensitivity of this cell is relatively high both in the red and also in the ultra-violet portion of the spectrum, being slightly less in the visible spectral Therefore long wave red is used for illuminating the cell for scanning the blue-green sound record.

If the source of light used for the sound reproducing apparatus is one giving white light or a mixture, of different kinds of rays lying within different spectral ranges, and the light-sensitive cell used is sensitive for a wide range of, or for thewhole of, the spectrum, the separation of the sound records is preferably eiected with the aid of colour lters which may be arranged in front' of or behind the lm. However, if selectively light-sensitive photo-cells are employed, the sound film may be illuminated with White light or with a light containing different rays of the spectrum, and the selective reproduction of the individual sound reproduction is. attained by changing corresponding light sensitive cells. In the above mentioned example of mutually independent red and blue sound records a cell having its maximum sensitivity in the red can be employed in order to reproduce the blue sound record whereas for reproducing the red sound record a cell having its maximum sensitivity in the blue is employed. I At the same timeadditional filters can also be used. 1f, in the film above described, each of the three diiferent layers contains a sound record, that is a purple-red, a yellow and a blue-green sound record, the purplered sound record is scanned with green light, which is not absorbed or weakened by the blue` green nor by the yellow layer. The yellow sound record is reproduced with the aid of blue light which is n ot influenced either by the purple or by the blue sound record, and iinally the bluelgreen sound record is reproduced with the aid of red rays for which both the yellow and the purple-red sound records are translucent. When substantially white light is used to illuminate the sound records selectively green, blue and red sensitive cells are employed for the individual reproductions. These cells can either be individually brought, as required, into the path of the light or they can be all initially situated in the path of the rays and may be individually switched in or out of the circuit by making and breaking the electric connection thereto. When other colour- 'ings are used for the individual layers the particular filters or light sensitive cells necessary for the reproduction are determined by the condition that each record must be scanned with light which is absorbed by the sound record to be reproduced, but passes through the other sound records unweakened. For the selective reproduction of the individual sound records, light from a practically panchromatic source of light can also be spectrally split up by prisms. grids or similar optical means and the resultant practically mono-chromatic ray portions employed for scanning the different sound tracks. In this method of reproduction the device used for splitting up the light, for example the prism, is arranged between the substantially panchromatic source of light and the photo cell or cells in such a manner that the resultant substantially mono-chromatic portions of the rays can be selectively directed through the reproducing slit and the sound record on to the photo cell.Y A prism may, for example, be rotatably mounted so that it projects either substantially mono-chromatic blue or substantially mono-chromatic red light on to the sound track. In the case of a iilm, which has for examplepartly overlapping sound records with superposed layers in blue and in red colours,

either one or other of the language versions of the film text is converted into sound. The use of substantially mono-chromatic light has the advantage that the range of absorption of the individual dyestu's may overlap to a certain extent provided the colour of the mono-chromatic light being employed is absorbed by the dyestuff in question and the other dyestuns allow the passage of this mono-chromatic light.

If, however, light of a relatively wide spectral range is employed for the reproduction, difficulty may be experienced in finding dyestuifs which have a sufficiently strong absorption in one spectral range whilst still being absolutely permeable in the other spectral range. In particular, bluegreen dyestuffs, the main absorption range of which is in the red spectral range. have also a noticeable absorption in green and blue. If, for example. a blue-green sound record according to the present process is covered by a different yellow sound record. as in the example above indicated. and if it is desired to reproduce the yellow sound record with blue light. this blue light will be influenced. even if only to a slight extent. also by the blue-green sound record. This variation of the light used for the reproduction of the yellow sound record. caused by the blue-green sound record. has a disturbing eii'ect on the reproduction of the yellow sound record. Now it has been found that this disturbing phenomenon can be eliminated in the following mannerz- From the blue-green sound record a coloured, preferably weak yellow. negative is produced in the film, the colour and density of this negative being such that it has, in the blue light with which the yellow coloured sound record is reproduced. the same absorption intensity for the said blue light as the positive picture of the bluegreen sound record (which is chiefly red absorbent). Thus the variations of the blue light due to the blue-green positive sound record, are balanced by equal and opposite variations produced by the absorption of the weak yellow negative. The blue light is then uniformly weakened and freed from uctuations by the positive bluegreen sound record and by its differently coloured negative. The photo-electric cells are not subjected to varying influences by the uniform weakening and consequently no disturbance of the sound reproduction is caused.

Example 2.-Illustrated by Figure 3. The sound image e is copied in the manner described above from a positive sound copy original into the blue-green, green-sensitive layer d of the three-coloured layer lm. The second sound image f is likewise copied from another positive sound copy original into the yellow layer b on the other side of the support a. In this yellow layer b a record g, is also made, also with a green copying light, from a weak negative-copy original identical with the positive copy copied on the blue-green side. After the selective destruction of the dyestuff, as indicated in Example 1 above, there is in the film a positive blue-green picture of the one sound record on one side of the support and on the other side of the support a yellow positive picture of the other sound record and also a weak negative record y of the first bluegreen 'sound record present o n the other side and arranged in juxtaposition to its corresponding positive e. Therefore, in this case, the Weak negative record g lies in a different layer to the corresponding positive record e, namely in the layer which from the outset contains the dyestuff which is intended for the weak negative picture.

Example 3,-Illustrated yby Figure 4. The s'ound records e and f for the blue-green and for the yellow layers d and b are copied in exactly the same manner as set forth in Example 1. The destruction of the dyestuff is likewise effected in the same manner and with the same media. After the selective destruction of the dyestuffs the silver picture in the whole film-is converted by treatment in a bath of copper sulphate and sodium chloride into a` silver compound capable of being removed by fixing in known manner. At the sound track portion the blue-green side of the film is treated with a reducing medium which converts the silver salt into metallic silver. For this purpose a solution of sodium hydrosulphite is applied on to the film on the .blue-green' side in the area of the sound trackby means of' a roller or by means of a sponge or by any othervv suitable means. The whole film isl then fixed in a fixing bath in the usual manner. At this stage a-chloracetoacetic ester grns 2 Acetone ccs-- 20 Diethyl-paraphenylenediamine .gms-.. 2 Water ccs-- 100 This solution acts as developer and at the same time as dyestuff forming' solution (colour development) At the points where the exposed silver chloride is present metallic silver and yellow dyestui is formed. The time during which the solution acts is chosen so that only a small quantity of yellow dyestuii is formed. The silver is bleached out in known manner.l In the bluegreen layer d there is then, in addition to the blue-green component picture in the picture portion and the blue-green positive sound record e,

a weak yellow coloured negative h of the same sound record and arranged in juxtaposition thereto. In this case, therefore, the positive sound record and the negative weak differently coloured sound record lie in one and the same layer.

Example 4.-Illustrated in Figure 5. The two positive sound records are copied in the two outer layers of the material in the manner vdescribed in Examples 1 to 3. The negative of the positive sound record which has been copied into the blue-green layer is copied into the middle layer c with a red copying light. The remaining treatment is carried out as described in Examples 1 and 2. In this case, the negative sound record j lies in the purple red coloured layer as a purple red negative picture arranged in juxtaposition to its corresponding positive e. During the reproduction of this film, in addition to the blue copying light which is necessary for reproducing the yellow sound record, the lm is illuminated with so much green light that the fluctuations, which are caused by the positive blue-green sound record, are compensated by the uctuations which result from the purple coloured negative of this sound record.

The invention is not restricted to the examples indicated, but the layers can be coloured in other manners and diiierently sensitized than indicated. Furthermore, the individual sound record need not be, as above indicated, copied in the outer layers, or be present in the colours given by way of example. Moreover, other devices from those indicated by way of example can be used for exhibiting the sound iilm. As is well known various reproducing devices may require sound records of opposite sign. Hence the terms positive and negative are to be understood as merely a designation of the mutual relationship between the record to be reproduced and the record to be used for compensating purposes. The method indicated above of producing the coloured picture, although it appears most advantageous, is only to be taken as by way of example. The term juxtaposition as used herein is dened as meaning broadly that a positive sound record which is in juxtaposition to a negative sound record has its points of maximum density corresponding to points of minimum density of the negative sound record.

It is already known to produce in each of several layers of a iilm a coloured sound record, the individual coloured records lying exactly superposed and corresponding to a single sound record. As distinct therefrom with the present invention a sound lm is produced in which the sound track contains several mutually independent sound records, that is particularly a sound iilm in which each of the mutually independent sound records corresponds to a different language version of the iilm text. These individual records are, in the reproduction of the film, not reproduced simultaneously, but selectively separated and reproduced as desired for the sound reproduction in the corresponding language version. The sound records are also not mutually independent in the known system in which the sound records are applied, for example, to the right and left halves of films, each of the same being reproduced at the same time in co-ordinated loudspeakers in order, for example, to render more realistic the reproduction of a dialogue in spacially separated loudspeakers. In this case, the two sound records are also played simultaneously and not separated from one another as independent sound records. This is also the case if a sound record is split up into a record of the high frequencies and into a record of the low frequencies, which, during the reproduction, are again reproduced simultaneously.

I claim:-

1. A multi-color sound film comprising a support, a plurality of photographic layers on said support, one of said layers having therein a colored positive photographic sound record, another of said layers having therein a differently colored and independent positive photographic sound record in partial superposition with respect to said first sound record, and one of said layers having therein a colored negative image of one of said sound records arranged in juxtaposition to its corresponding positive, the color of said negative image being absorbent for light chieiiy transmitted by the corresponding positive but highly absorbed by the other positive.

2. In a multi-color sound iilrn comprising a support, a plurality of photographic layers on said support, one of said layers having therein a colored positive photographic sound record highly absorbent for light in a predetermined spectral region, a second layer having therein a differently colored and independent positive photographic sound record highly absorbent for light in a second spectral region and located in partial superposition with respect to said first sound record, said second layer having therein a negative image of said first referred to sound record, the color and density of said negative image being such that it balances the absorption of said first referred to sound record in said second spectral region.

3, A multi-color sound lm comprising a support, a plurality of photographic layers on said support, o ne of said layers having therein a colored positive photographic sound record highly absorbent for light in a predetermined spectral region, another of said layers having therein a differently colored and independent positive photographic sound' record highly absorbent for light in a second spectral region and located in partial superposition with respect to said i'lrst sound record, said rst referred tolayer having therein a negative image of the positive sound record located in that layer which is arranged in juxtaposition to said corresponding positive, the color and density of said negative image being such that it balances the absorption of said corresponding positive in said second spectral region.

4. A multi-color sound lm comprising a support, three photographic layers on said support, one of said layers having therein a colored positive photographic sound record highly absorbent for light in a predetermined spectral region, a second layer having therein a differently colored and independent positive photographic sound record highly absorbent for light in a second spectral region and located in partial superposition with respect to said iirst referred to sound record, a third layer having therein a negative image of said first referred to sound record dif-l 5. A sound film comprising a support, a plurality of photographic layers on said support, each having a picture area and a sound area, the picture areas of the different layers including part pictures in diierent colors, the sound area of one of said layers having therein a colored positive photographic sound record of the same color as that forming the colored part picture in the picture area of the same layer, another layer havingA in the sound area a diierently colored negative photographic sound record corresponding to said positive photographic sound record and arranged in juxtaposition thereto, the color of the positive sound record being absorbent for light chiey transmitted by the negative sound record and the color of the negative sound record being absorbent for light chiefly transmitted by the positive sound record.

6. A multi-color film comprising a support, a plurality of photographic layers on said support, one of said layers having therein a colored positive photographic record, another of said layers having therein a differently colored and independent positive photographic record in partial superposition with respect to said first photographic record, and one of said layers having therein a colored negativA image of one of said positive photographic records arranged in juxtaposition to its corresponding positive, the color of said negative image being absorbent for light chiefly transmitted by the corresponding positive but highly absorbed by the other positive.

WALTER IVIICHAELIS. 

